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using System;
interface IContravariant<in T>
{
}
interface ICovariant<out T>
{
}
class D
{
public static bool Contra<T> (IContravariant<T> e1, IContravariant<T> e2)
{
Console.WriteLine (typeof (T));
return typeof (T) == typeof (string);
}
public static bool Covariant<T> (ICovariant<T> e1, ICovariant<T> e2)
{
Console.WriteLine (typeof (T));
return typeof (T) == typeof (object);
}
public static bool CovContCont<T> (ICovariant<T> e1, IContravariant<T> e2, IContravariant<T> e3)
{
Console.WriteLine (typeof (T));
return typeof (T) == typeof (string);
}
public static bool ContCovContCov<T> (IContravariant<T> e1, ICovariant<T> e2, IContravariant<T> e3, ICovariant<T> e4)
{
Console.WriteLine (typeof (T));
return typeof (T) == typeof (string);
}
public static bool CovCovCont<T> (ICovariant<T> e1, ICovariant<T> e2, IContravariant<T> e3)
{
Console.WriteLine (typeof (T));
return typeof (T) == typeof (string);
}
public static int Main ()
{
ICovariant<object> a = null;
ICovariant<string> b = null;
if (!Covariant (a, b))
return 1;
IContravariant<string> a_1 = null;
IContravariant<object> b_1 = null;
if (!Contra (a_1, b_1))
return 2;
ICovariant<string> a_2 = null;
IContravariant<object> b_2 = null;
IContravariant<string> c_2 = null;
if (!CovContCont (a_2, b_2, c_2))
return 3;
IContravariant<object> a_3 = null;
ICovariant<string> b_3 = null;
IContravariant<string> c_3 = null;
ICovariant<string> d_3 = null;
if (!ContCovContCov (a_3, b_3, c_3, d_3))
return 4;
Console.WriteLine ("ok");
return 0;
}
}
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